Merge branch 'net-ethernet-Mark-expected-switch-fall-throughs'

Gustavo A. R. Silva says:

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net: ethernet: Mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, this patchset aims
to add some annotations in order to mark switch cases where we are
expecting to fall through.
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Signed-off-by: David S. Miller <[email protected]>